Enhanced Specific Heat of Silica Nanofluid

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
Donghyun Shin ◽  
Debjyoti Banerjee
Keyword(s):  
Electron Microscopy ◽  
Specific Heat ◽  
Unit Volume ◽  
High Surface ◽  
High Surface Area ◽  
Lithium Carbonate ◽  
Sem Image ◽  
Surface Energies ◽  
Transmission Electron ◽  
The Stability

Silica nanoparticles (1% by weight) were dispersed in a eutectic of lithium carbonate and potassium carbonate (62:38 ratio) to obtain high temperature nanofluids. A differential scanning calorimeter instrument was used to measure the specific heat of the neat molten salt eutectic and after addition of nanoparticles. The specific heat of the nanofluid was enhanced by 19–24%. The measurement uncertainty for the specific heat values in the experiments is estimated to be in the range of 1–5%. These experimental data contradict earlier experimental results reported in the literature. (Notably, the stability of the nanofluid samples was not verified in these studies.) In the present study, the dispersion and stability of the nanoparticles were confirmed by using scanning electron microscopy (SEM). Percolation networks were observed in the SEM image of the nanofluid. Furthermore, no agglomeration of the nanoparticles was observed, as confirmed by transmission electron microscopy. The observed enhancements are suggested to be due to the high specific surface energies that are associated with the high surface area of the nanoparticles per unit volume (or per unit mass).

scholarly journals Pd Nanoparticles Stabilized on the Cross-Linked Melamine-Based SBA-15 as a Catalyst for the Mizoroki–Heck Reaction

2021 ◽  
Author(s):  
Ayat Nuri ◽  
Abolfazl Bezaatpour ◽  
Mandana Amiri ◽  
Nemanja Vucetic ◽  
Jyri-Pekka Mikkola ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Inductively Coupled Plasma ◽  
High Surface ◽  
High Surface Area ◽  
Coupling Reaction ◽  
Pd Nanoparticles ◽  
Significant Activity ◽  
Inductively Coupled ◽  
Transmission Electron ◽  
Ft Ir

AbstractMesoporous SBA-15 silicate with a high surface area was prepared by a hydrothermal method, successively modified by organic melamine ligands and then used for deposition of Pd nanoparticles onto it. The synthesized materials were characterized with infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), nitrogen physisorption, scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), nuclear magnetic resonance (NMR) and inductively coupled plasma (ICP-OES). The catalyst was effectively used in the Mizoroki–Heck coupling reaction of various reactants in the presence of an organic base giving the desired products in a short reaction time and with small catalysts loadings. The reaction parameters such as the base type, amounts of catalyst, solvents, and the temperature were optimized. The catalyst was easily recovered and reused at least seven times without significant activity losses. Graphic Abstract

Magnetic Fe3O4@C nanoparticles as adsorbents for removal of amoxicillin from aqueous solution

2013 ◽  
Vol 69 (1) ◽  
pp. 147-155 ◽  
Author(s):  
Babak Kakavandi ◽  
Ali Esrafili ◽  
Anoushiravan Mohseni-Bandpi ◽  
Ahmad Jonidi Jafari ◽  
Roshanak Rezaei Kalantary
Keyword(s):  
Electron Microscopy ◽  
Activated Carbon ◽  
Kinetic Models ◽  
High Surface ◽  
High Surface Area ◽  
Order Kinetic ◽  
Magnetic Composites ◽  
Factors Affecting ◽  
Transmission Electron ◽  
Pseudo Second Order

In the present study, powder activated carbon (PAC) combined with Fe3O4 magnetite nanoparticles (MNPs) were used for the preparation of magnetic composites (MNPs-PAC), which was used as an adsorbent for amoxicillin (AMX) removal. The properties of magnetic activated carbon were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Brunaeur, Emmett and Teller and vibrating sample magnetometer. The operational factors affecting adsorption such as pH, contact time, adsorbent dosage, initial AMX concentration and temperature were studied in detail. The high surface area and saturation magnetization for the synthesized adsorbent were found to be 671.2 m2/g and 6.94 emu/g, respectively. The equilibrium time of the adsorption process was 90 min. Studies of adsorption equilibrium and kinetic models revealed that the adsorption of AMX onto MNPs-PAC followed Freundlich and Langmuir isotherms and pseudo-second-order kinetic models. The calculated values of the thermodynamic parameters, such as ΔG°, ΔH° and ΔS° demonstrated that the AMX adsorption was endothermic and spontaneous in nature. It could be concluded that MNPs-PAC have a great potential for antibiotic removal from aquatic media.

scholarly journals Synthesis and Characterization of Hierarchical Porousα-FeOOH for the Adsorption and Photodegradation of Rhodamine B

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Jianliang Cao ◽  
Gaojie Li ◽  
Yan Wang ◽  
Guang Sun ◽  
Hari Bala ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Rhodamine B ◽  
Uv Light ◽  
Low Cost ◽  
High Surface ◽  
High Surface Area ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Hierarchical Porous ◽  
Templated Method

Hierarchical porousα-FeOOH nanoparticles were controlled and prepared via a facile polystyrene (PS) microspheres-templated method. Theα-Fe2O3was obtained by the calcination of the as-preparedα-FeOOH. The resulting nanoparticles were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N2-sorption techniques. The adsorption and photodegradation of Rhodamine B performance were evaluated under UV light at room temperature. The results indicated that the photocatalytic activity of theα-FeOOH nanoparticles is superior toα-Fe2O3-200 andα-Fe2O3-300 due to the hierarchically multiporous structure and high surface area. This convenient and low-cost process provides a rational synthesis alternative for the preparation of multiporous materials and the as-synthesis products have great foreground applications in many aspects.

Ni-doped, urchin-like Bi2S3 particles for electrocatalytic oxidation of glucose

2021 ◽  
pp. 2150006
Author(s):  
Biao Wang ◽  
Ya Liu ◽  
Xu Huai ◽  
Yuqing Miao
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Electrocatalytic Oxidation ◽  
High Surface ◽  
High Surface Area ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Capacitance Current ◽  
Oxidation Of Glucose

In order to develop non-noble metal-based electrocatalysts for glucose oxidation, the Ni-doped, urchin-like Bi2S3 particles were prepared by a solvothermal method using the solvent of ethylene glycol/H2O. The obtained products were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The background signal from capacitance current is relatively low and the electrocatalytic oxidation current of glucose relatively high due to the urchin-like nanostructure of Bi2S3 particles and high surface area where the presence of Bi also improves the electrocatalytic performance of NiII/NiIII shift.

scholarly journals Electrical Conductivity Based Ammonia Sensing Properties of Polypyrrole/MoS2 Nanocomposite

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3047
Author(s):  
Sharique Ahmad ◽  
Imran Khan ◽  
Ahmad Husain ◽  
Anish Khan ◽  
Abdullah M. Asiri
Keyword(s):  
Electron Microscopy ◽  
Electrical Conductivity ◽  
Active Sites ◽  
High Surface ◽  
High Surface Area ◽  
High Sensitivity ◽  
Ambient Air ◽  
Sensing Properties ◽  
Ammonia Sensing ◽  
Transmission Electron

Polypyrrole (PPy) and Polypyrrole/MoS2 (PPy/MoS2) nanocomposites were successfully prepared, characterized and studied for ammonia sensing properties. The as-prepared PPy and PPy/MoS2 nanocomposites were confirmed by FTIR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction), SEM (scanning electron microscopy) and TEM (transmission electron microscopy) techniques. The ammonia sensing properties of PPy and PPy/MoS2 nanocomposites were studied in terms of change in DC electrical conductivity on exposure to ammonia vapors followed by ambient air at room temperature. It was observed that the incorporation of MoS2 in PPy showed high sensitivity, significant stability and excellent reversibility. The enhanced sensing properties of PPy/MoS2 nanocomposites could be attributed to comparatively high surface area, appropriate sensing channels and efficiently available active sites. The sensing mechanism is explained on the basis of simple acid-base chemistry of polypyrrole.

SYNTHESIS AND CHARGE–DISCHARGE PROPERTIES OF POROUS CO3O4 NANOROD BUNDLE ELECTRODE

NANO ◽  
2012 ◽  
Vol 07 (05) ◽  
pp. 1250036 ◽  
Author(s):  
FEI TENG ◽  
JUN WANG ◽  
MINDONG CHEN ◽  
DENNIS DESHENG MNEG
Keyword(s):  
Electron Microscopy ◽  
High Surface ◽  
High Surface Area ◽  
Lithium Ion ◽  
Nitrogen Adsorption ◽  
X Ray ◽  
Transmission Electron ◽  
Rate Capacity ◽  
Nanorod Bundle ◽  
Charge Discharge

The Co3O4 nanorod bundles are synthesized by a hydrothermal method. The samples are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED), X-ray powder diffractometer (XRD), and nitrogen adsorption. It is important that the as-obtained Co3O4 nanorod bundles are assembled by nanoparticles. The porous nanorod bundle electrode exhibits a higher rate capacity and a higher reverse capability for lithium ion battery than the solid nanorods, which is attributed to the high surface area and the porous structure.

Transmission Electron Microscopy Studies of Pd Encapsulation by Ceria-Zirconia Oxides

1998 ◽  
Vol 4 (S2) ◽  
pp. 724-725
Author(s):  
J. C. Jiang ◽  
X. Q. Pan ◽  
G. W. Graham ◽  
R. W. McCabe ◽  
J. Schwank
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
Surface Area ◽  
High Speed ◽  
High Surface ◽  
Silicon Crystal ◽  
High Surface Area ◽  
Thermal Environments ◽  
Transmission Electron

High-temperature catalysts containing Pd supported on high-surface area ceria-zirconia are optimum materials for fuel economy when automotive engines operate under high speed or load conditions. A prerequisite for developing such thermally stable catalysts is to gain a good understanding of the thermal deactivation modes contributing to the aging and degradation of catalysts in harsh thermal environments. It was discovered by X-ray diffraction that upon hightemperature aging, Pd may sinter into large (about 10 nm diameter) particles and become encapsulated in the ceria-zirconia. To confirm this conclusion, a prototype high-temperature catalyst containing Pd supported on high-surface area ceria-zirconia, aged at temperature above 1100 °C is studied by transmission electron microscopy (TEM).The ceria-zirconia supported Pd (0.25 wt%) catalyst was aged at 1105 °C and calcined at 700 °C for 2 h. For TEM sample preparations, first of all, a large-size aggregate with diameter about 1 mm was selected and sandwiched between by two pieces of silicon crystal.

Characterization of an Inorganic Cryptomelane Nanomaterial Synthesized by a Novel Process Using Transmission Electron Microscopy and X-Ray Diffraction

2008 ◽  
Vol 14 (4) ◽  
pp. 328-334 ◽  
Author(s):  
Longzhou Ma ◽  
Thomas Hartmann ◽  
Marcos A. Cheney ◽  
Nancy R. Birkner ◽  
Pradip K. Bhowmik
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Surface ◽  
High Surface Area ◽  
Rietveld Analysis ◽  
X Ray ◽  
Transmission Electron ◽  
Potential Applications ◽  
Diffraction Patterns ◽  
Crystallographic Planes

Layer- and tunnel-structured manganese oxide nanomaterials are important because of their potential applications in industrial catalysis. A novel soft chemistry method was developed for the synthesis of inorganic cryptomelane nanomaterials with high surface area. Bright field transmission electron microscopy (BF-TEM) and high-resolution transmission electron microscopy (HRTEM) techniques were employed to characterize this nanomaterial. A nanosized material with fibrous texture comprised of 140–160 nm striations was identified by BF-TEM imaging. HRTEM images show multiple atomic morphologies such as “helix-type,” “doughnut-like,” and tunnel structures lying on different crystallographic planes. The crystallographic parameters of this material were analyzed and measured by X-ray powder diffraction (XRD) showing that the synthesized nanomaterial is single phased and corresponds to cryptomelane with major diffraction peaks (for 10° < 2θ < 60°) at d-spacing values of 6.99, 4.94, 3.13, 2.40, 2.16, 1.84, 1.65, and 1.54 Å. A “doughnut-like” crystal structure was confirmed based on the crystallographic data. Structure and lattice parameters refinement was performed by XRD/Rietveld analysis. Simple simulation of HRTEM images and selected area diffraction patterns were applied to interpret the HRTEM images as observed.

scholarly journals Synthesis and characterization of LaMnO3 nanocrystals and graphene oxide: fabrication of graphene oxide–LaMnO3 sensor for simultaneous electrochemical determination of hydroquinone and catechol

2019 ◽  
Vol 9 (4) ◽  
pp. 255-267 ◽  
Author(s):  
Sedighe Akbari ◽  
Mohammad Mehdi Foroughi ◽  
Hadi Hassani Nadiki ◽  
Shohreh Jahani
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Simultaneous Determination ◽  
High Surface ◽  
High Surface Area ◽  
Electrochemical Determination ◽  
Great Decrease ◽  
X Ray ◽  
Transmission Electron

For the first time, a new method for preparation of graphene oxide-LaMnO3 (GO-LaMnO3) nanocompositeas a material of electrochemical sensor for simultaneous determination of catechol (CT) and hydroquinone (HQ) is developed. LaMnO3 nanoparticles have been characterized by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX) technique. Due to the excellent catalytic activity, enhanced electrical conductivity and high surface area, the simultaneous determination of HQ and CT with two well-defined peaks has been achieved at the GO-LaMnO3 modified electrode. Comparing with unmodified electrodes, the oxidation currents of HQ and CT increased remarkably. Also, the result exhibited a great decrease in anodic overpotentialresulting in about 150 mV negative shift of potential. The catalytic peak current values are found linearly dependent on the HQ and CT concentrations in the range of 0.5–433.3 and 0.5–460.0 μM with sensitivity of 0.0719 and 0.0712 μA μM-1, respectively. The detection limits for HQ and CT are determined as 0.06 and 0.05 μM, respectively.

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